1. Field of the Invention
The present invention relates to an optical member, such as a polarizing plate, that may be easily peeled off after being adhered by adhesive to liquid crystal cell etc. and a liquid crystal display with the optical member used therein.
2. Description of the Prior Art
In liquid crystal display (LCD), a constitution is generally used in which a polarizing plate, an elliptically polarizing plate, a polarizing plate with a compensating film, a polarizing plate with reflective/transflective layer, and a polarizing plate with a brightness enhanced film are laminated onto a liquid crystal cell through adhesive. In manufacturing method of such LCD, for the purpose of preventing of variation in quality, and of improving efficiency of LCD assembly line, etc., a method is used in which optical member is adhered onto a liquid crystal cell in a state where adhesive layer comprising acrylic derived adhesive etc. is applied beforehand thereon. In a process in which the optical members is adhered to liquid crystal cell, when a position where the optical member etc. is to be adhered shifts or foreign matters enter, the optical members, such as a polarizing plate, are peeled off from a liquid crystal cell, and panels, such as liquid crystal cell, are reused. In that case, first, a part of the optical member is peeled off with edge tool etc. from a corner portion, a trigger for peeling is prepared and then the whole optical member is peeled off gradually from the portion.
However, in that case a difficulty in preparation of a trigger and a large amount of peeling strength in subsequent peeling process worsen workability. Moreover, if a very large peeling strength, there is a possible problem to change cell gaps of a liquid crystal cell, and of reducing display quality or damaging panels.
Alternatively, although adhesives with a low-adhesive strength raise a peeling property, these low-strength adhesives induce a problem that peeling of a polarizing plate adhered to a liquid crystal cell is caused after a durability examination of heating, humidification, etc. Thus, it was difficult to be compatible in peeling property and durability.
Therefore, an object of the present invention is to provide an optical member in which strength required for peeling may be reduced without decreasing adhesive strength of the adhesives and in which a trigger for peeling is easily prepared. And an other object of the present invention is to provide a liquid crystal display using said optical member
The present inventors wholeheartedly carried out research that the above-mentioned object should be attained. It was found by the present inventors that in case of peeling, as stiffness of peeling an optical member is stronger, a peeling strength (adhesive strength) becomes smaller, but when the stiffness is too strong, a preparation of a trigger for peeling becomes difficult and as a result workability is impaired. And thus the present invention was completed.
That is, an optical member of the present invention is an optical member comprising an optical material or a laminated body of the optical materials in a shape a sheet or a film and an adhesive layer at least on one side thereof, wherein a repulsive force of the optical member deformed at 180xc2x0 in radius of 25 mm with 25 mm width shows 0.2 to 0.8 N. Usually the deformation is carried out in a shape of a semicircle deformed at 180xc2x0 in radius of 25 mm with 25 mm width, the form of deformation is not strictly limited in the shape of a semicircle, but a case maybe permitted where curvature is locally different from other portion or an error on work exists.
In the above-mentioned optical member, it is preferable that the optical material or a laminated body of the optical material is a polarizing plate, a reflection type polarizing plate, a transflective layer type polarizing plate, or a polarized light separation polarizing plate or a laminated body obtained by laminating a retardation plate with each of the above-mentioned polarizing plate.
On the other hand, a liquid crystal display of the present invention comprising at least one above-mentioned optical member is adhered on a liquid crystal cell.
Since repulsive force shows 0.2 to 0.8 N in an optical member of the present invention when deformed at 180xc2x0 in radius of 25 mm with 25 mm width, as results of Example show, a strength required for peeling may be decreased without decrease in adhesive strength of adhesive itself to enable easy formation of trigger for peeling. When the repulsive force is less than 0.2 N, an effect becomes inadequate in making a strength required for peeling reduced to impair workability, and on the contrary, if the repulsive force exceeds 0.8 N, it will be hard to prepare a trigger for peeling and workability will also be impaired.
In a case the material or a laminated body of the optical materials is a polarizing plate, a reflection type polarizing plate, a transflective layer type polarizing plate, or a polarized light separating polarizing plate or a laminated body obtained by laminating a retardation plate with each of the above-mentioned polarizing plates, when each of the plated is adhered onto a liquid crystal cell etc. through an adhesive layer, a problem of the above-mentioned peeling may occur during work. Therefore, the present invention providing the above-mentioned function and effect will become especially useful.
On the other hand, since at least one optical member having the above-mentioned function and effect is adhered onto a liquid crystal cell in a liquid crystal display of the present invention, in the case where the optical member is peeled off from the liquid crystal cell, a strength required for peeling may be decreased without decrease in adhesive strength of adhesive itself to enable easy preparation of a trigger for peeling.